1. Technical Field
The invention relates to geofencing for vehicles, and more particularly, to providing a simplified method for determining if a vehicle's position is within or without an irregular geofence.
2. Description of the Problem
A geofence may be defined in part as a virtual spatial boundary. Geofences are a byproduct of the marriage of mobile, inexpensive telecommunications platforms and data processing systems. They are enhanced in accuracy by making use of global positioning systems which allow accurate, precise determination of the location of both the boundary of a geofence and position of a mobile platform relative to the geofence. A geofence typically operates by triggering of a physical response through the mobile, location sensitive device when the device crosses a boundary, though the system on which the method is implemented may simply operate to note the fact of the crossing to an operator. The spatial location of geofences have commonly been established by selecting a point feature, which may be a point defined by latitude and longitude, and then defining either a radius, or major/minor axis for the point feature, to establish a boundary around the point.
United States Pat. Appl. Pub. 2006/02003005 described construction, using graphical user interface tools, of geofences with boundaries corresponding to real world objects. The area enclosed by such a fence would typically be an irregular polygon, the expression of which might result from simple selection of an object to be enclosed by the fence, such as the campus of a school. An irregular geofence was recognized as more readily applied to real world situations. Among the issues raised with respect to such irregular polygon shaped fences was the difficulty of fully and correctly representing the actual polygon for devices with limited data processing resources. The reference provided the contingency of “decimating” the polygon to avoid overwhelming the resources of such devices.